Ven Te Chow Hydrosystems Laboratory

Facilities: Large Oscillating Water-sediment Tunnel

This flume, one of the largest of its kind in the world, is currently being used to study flow-object and moveable bed problems, along with sediment transportation, ripple formation, incipient motion, bedload and suspended sediment motion. In the near future, boundary layer flows and turbulence studies will be started.

The tunnel is U shaped, with one leg containing the three pistons and the other a free leg, called the receiver chamber. Tests can be performed under waves and/or current. A pipeline system with two centrifugal pumps is used for imposing current. The pistons can generate different shaped pulses (i.e. square, triangle, or sine) into the water flow.

The tunnel is 79 ft 9 in (24.3 m) long, 2 ft 8 in (0.8 m) wide (inner width), and 4 ft (1.2 m) high (inner height). The maximum water height is 18 ft 4 in (5.6 m) and the piston stroke is 4 ft 7 in (1.4 m). The drive system is hydraulic and is capable of a maximum velocity of 2 m/s, maximum acceleration of 6 m/s², and a period of 1 s to 18 s. The pumps are three close coupled, end suction centrifugal pumps with a maximum combined discharge of 240 l/s. The standard sediment bed depth is 2 ft (0.6 m).

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Large oscillating water-sediment tunnel.

Concrete cylinder being buried under oscillatory flow.